Method of Regeneration spent Iron Electroplating Solutions with Concomitant Desulfurization of Coal

ABSTRACT

Spent iron electrolyte solutions withdrawn from iron plating baths containing Fe3 are regenerated by centrifugally contacting the electrolyte with a bed of coal particles containing iron sulfides centrifugally fixed on the perforated sidewalls of a rotating reaction chamber. The process causes the rapid reduction of the FeCl3 to FeCl2 with the concomitant removal of the iron sulfides from the coal.

United States Patent [191 Colwell METHOD OF REGENERATION SPENT IRON ELECTROPLATING SOLUTIONS WITH CONCOMITANT DESULFURIZATION OF COAL [75] Inventor: Robert E. Colwell, Palos Park, III.

[73] Assignee: Continental Can Company, Inc.,

New York, NY.

[22] Filed: Mar. 21, 1973 [21] Appl. No.: 343,330

[52] US. Cl 204/48, 44/1 R, 210/60, 2l0/75, 423/153, 423/460, 423/461, 423/571 [51 J Int.C1 C1019/02,C23b s /o4 c o b 1 7/0; [58] Field of Search 210/60, 75; 44/1 R; 201/17; 423/153, 460, 461, 571; 204/48,

[56] References Cited UNITED STATES PATENTS 2,653,905 9/1953 Aannerud 204/112 0 o a" o 51 Feb. 4, 1975 2,726,148 12/1955 McKinley et al 44/1 R 3,768,988 10/1973 Meyers 44/1 R OTHER PUBLICATIONS R. E. Brewer et al., Ind. & Eng. Chem., Vol. 41, No. 9, p. 2044, (1949).

Primary Examiner--G. L. Kaplan Attorney, Agent, or Firm-Paul Shapiro; Joseph E. Kerwin; William A. Dittmann [57] ABSTRACT Spent iron electrolyte solutions withdrawn from iron plating baths containing Fe are regenerated by centrifugally contacting the electrolyte with a bed of coal particles containing iron sulfides centrifugally fixed on the perforated sidewalls of a rotating reaction chamber. The process causes the rapid reduction of the FeCl to FeCl with the concomitant removal of the iron sulfides from the coal.

4 Claims, 1 Drawing Figure u o 9 0 o co M c 06 PATENTED FEB 4l975 METHOD OF REGENERATION SPENT IRON ELECTROPLATING SOLUTIONS WITH CONCOMITANT DESULFURIZATION OF COAL BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to the regeneration of spent iron plating electrolyte solutions and more particularly to the regeneration of spent electrolyte solutions using coal particles having substantial iron pyrite I content.

2. The Prior Art Combustion of coal for heat, steam, and electrical power generation is by far the largest single source of atmospheric sulfur dioxide pollution in the United States; it currently accounts for about two thirds of the total sulfur oxide emissions. Federal government standards limit the discharge of sulfur dioxide into the atmosphere to 1.2 pounds per million Btus of heat input for solid fossil fuel combustion operations generating more than 250 million Btus per hour. This emission limit corresponds to a maximum sulfur content restriction of 0.6 0.8 percent for most Eastern coals. However, coal for utility consumption averages about 2.5 3.0 percent sulfur. The sulfur contained in the coal exists principally as ferrous sulfide (FeS commonly referred to as iron pyrites.

One method known to the art for the removal of iron pyrites is the Meyers process wherein the iron pyrites are leached from coal utilizing aqueous solutions of ferric ions, Chemical Removal of Pyritic Sulfur from Coal by .l. M. I-Iamersa et al, Symposium on Environmental Pollution Control, American Chemical Society Division of Fuel Chemistry, Aug. 29-31, 1972, New York, N.Y.

In the Meyers process, coal containing iron pyrites is treated with an aqueous ferric chloride or sulfate solution at approximately 100C to convert the pyritic sulfur content to elemental sulfur and Fe. The aqueous solution is separated from the coal and the coal is washed to remove residual ferrous and ferric salt. The elemental sulfur which is dispersed in the coal matrix is then removed by vacuum distillation or extraction with a solvent such as toluene or kerosene. The resulting coal has a substantially reduced pyrite content and may be used as low sulfur fuel.

The chemical removal of iron pyrites using this process can be represented as follows:

2 Fe FeS Coal 3 Fe Coal S+ Coal extraction S (elemental) Coal 3 Fe O-l 3 Fe 3/2'[O=] It is also well known to the art as for example, US. Pat. Nos, 1,412,174, 1,862,745, 2,223,928, 2,316,917, 2,420,403 and US. Pat. No. 2,758,950, to electroplate iron articles such as sheets, foil, strips, tubes and the like wherein the iron is plated from an electroplating bath onto a suitably shaped cathode. Typically, the electroplating is accomplished with a highly concentrated FeCl solution. In the electroplating of iron using FeCl solutions, the cathode reaction is represented by the equation:

FeCl, 2e Fe 2 Cl and the anode reaction by the equation:

2 FeCl 2 Cl 2e 2 FeCl The commercial applications of electroplating iron structures are readily apparent. The direct production of iron sheet, tubes or containers from iron plating baths would replace the capital and energy costs of the blast furnaces, rolling mills and shaping equipment presently required for the production of these iron articles. Utilizing scrap iron derived from discarded auto- 0 mobiles, metal containers and the like would permit recycling of these materials and thereby alleviate the serious ecological problem of solid waste disposal with which our nation is presently confronted.

Although it has been long known that iron can be deposited from its solutions by electrolysis and the commercial aspects of iron electroplating readily apparent, the process has been little used except in the building up of undersized parts and in the production of high purity iron.

One problem encountered in the electroplating of iron articles which has retarded the commercial application of the process is that the plating reaction rapidly depletes Fe from the electrolyteand fresh electrolyte must be continuously fed to the electrolytic bath. Methods of regenerating the spent electrolyte are complex and costly.

One method of regenerating spent electrolyte is disclosed and claimed in copending patent application Ser. No. 300,071 filed Oct. 24, 1972, the disclosure of which is incorporated in the present application by reference.

In the method disclosed in patent application Ser. No. 300,071, iron particles and spent FeCl; electrolyte solution from an iron electroplating bath are charged to a rotating reaction chamber having sidewalls provided with a plurality of openings, the openings being of a size which is smaller than the size of the iron particles charged to the chamber. The chamber is rotated at a speed sufficient to cause the iron particles to be propelled outwardly under the influence of centrifugal force against the sidewalls of the chamber and to be fixed thereon to form a continuous bed of iron particles. The spent electrolyte solution charged to the chamber is propelled outward into contact with the iron particle bed and is caused to contact and move radially therethrough under the action of the same centrifugal force which fixes the particles on the chamber sidewalls. As the liquid reactant passes through the particle bed it reacts with the particle bed at an extremely high reaction rate in accordance with the equations:

The FeCl H reaction products then exit the chamber through the sidewall openings and are recovered.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a process for effecting the removal of iron sulfide from coal using spent electrolyte solution from iron plating baths wherein the spent electrolyte and coal particles containing iron sulfides are charged to a reaction chamber having a plurality of openings in its sidewalls, the size of the openings being smaller than the size of the coal particles. The chamber is rotated with sufficient rotational speed to generate a centrifugal force to cause the coal particles to be propelled outwardly against the walls of the chamber and be fixed thereon to form a continuous bed of particles. As the chamber is rotated, the spent electrolyte is propelled outward into contact with the coal particle bed fixed on the walls of the chamber and is caused to move radially therethrough under the action of centrifugal force, the spent iron electrolyte during its passage through the particle layer entering into chemical reaction with the iron sulfides contained in the coal particles whereby the iron sulfides are converted in to FeCl and sulfur. In the case of FeS the reaction proceeds in accordance with the equation: FeS, Coal 2 FeCl 3 FeCl 2 S The coal, after contact with the electrolyte is advanced through the reaction chamber by an oscillating pusher plate or other means, is washed to remove electrolyte, and is then discharged from the chamber.

DESCRIPTION OF THE DRAWING The FIGURE is an elevational view, in vertical section, schematically showing the essential construction and arrangement of a centrifugal apparatus suitable for use in the practice of the present invention.

PREFERRED EMBODIMENTS Referring now to the FIGURE, there is shown a centrifugal reactor 18 having a reaction chamber 19 operatively connected to a rotable shaft 20 which is mounted in bearing 21 and is driven by a power source (not shown). A casing 23 encloses the reaction chamber 19. Inlet pipe 24 provides means whereby a slurry of coal particles 26 of a predetermined size and containing about 0.2 to 20 or more iron pyrite mixed with spent electrolyte solution obtained from an iron plating bath are charged to the chamber 19.

The reaction chamber 19 is formed of a cylindrical perforated side wall 29 having a plurality of spaced openings 30 which are smaller in size than the size of the coal particles 26 fed to the chamber. Mounted within shaft 20 and adapted to oscillate within the chamber interior is distributor plate or disc 31. As the chamber 19 is caused to rotate about its axis by the rotation of the shaft 20, the coal particles supplied to the chamber interior 34 are caused to contact the rotating disc 31 and are continuously propelled'radially outward toward and onto the perforated walls of the chamber by the centrifugal force exerted thereon. As the particles are of a size larger than the wall openings, the particles cannot penetrate the wall and remain fixed thereto as a continuous layer or bed of particles 32. Plate 31 is caused to oscillate periodically, pushing the bed of coal particles toward discharge means 25 of the chamber 19. The spent electrolyte entering the interior chamber 34 upon impingement on the rotating disc 31 is thrown radially outward against the particle bed 32 fixed to the wall 29 by the centrifugal force generated by the rotating chamber 19. When the chamber 19 is rotated at a speed which generates sufficient centrifugal force to keep the particles 26 in fixed alignment with the walls 29 of the chamber 19, the same centrifugal force causes the liquid electrolyte to move radially through the bed 32. As the electrolyte moves through the bed 32, the iron pyrite contained in the coal particles is converted to FeCl and S by reaction with the FeCl dissolved in the electrolyte.

The treated coal particles having the iron pyrites removed therefrom and discharged from the reactor shown. The sulfur is easily separated from the coal particles by washing or other conventional separation means.

The coal and electrolyte slurry feed rate and rotational speed of the chamber 19 are generally selected so that only a fraction of the interstitial pore volume of the bed is filled with liquid electrolyte at any given time, and flooding of the bed is thereby avoided.

At a constant slurry feed rate, the bed filla'ge can be readily reduced by increasing the chamber rotational speed.

After being propelled through the particle bed 32, the regenerated electrolyte, comprised of substantially reduced concentrations of Fe and increased concentrations of FeCl;, is continuously expelled by the action of the centrifugal force from the interior chamber 34 through the spaced openings 30 in the side wall 29 and enters the chamber 35. The regenerated electrolyte is caused to outwardly flow from the chamber 35 by gravity or by pumping and is discharged from the chamber 35 through outlet 36 provided in the bottom of the chamber 35.

The regenerated electrolyte discharged from the chamber 35 through the outlet 36, may be recycled through the same or a series of similar centrifugal reac- 1 tors if more complete reduction of the Fe ion is desired or the regenerated electrolyte may be immediately purified to remove contaminants and pumped directly into the electrolyte supply means of an electro- FeS FeS S The roasted coal refuse can then be contacted with FeCl solution in the centrifugal reactor 18 just described to effect the removal of the FeS content in accordance with the equation: FeS 2 FeCl 3 FeCl S What is claimed is:

l. A process for effecting the regeneration of spent electrolyte solutions obtained from iron plating baths comprising the steps of: v

charging coal particles containing iron sulfides to a reaction chamber having a plurality of openings in its sidewalls, the size of the openings being smaller than the size of the particles,

rotating the chamber with sufficient rotational speed to generate a centrifugal force to cause the particlesto be propelled outwardly against the walls of the chamber and be fixed thereon to form a continuous bed of particles,

charging spent electrolyte solution comprised of an aqueous solution of Fe to the rotating chamber, the electrolyte solution being propelled outward into contact with the particle bed fixed on the walls of the chamber and caused to move radially therethrough under the action of centrifugal force, the Fe in the electrolyte solution during the passage of the solution through the particle layer entering into chemical reaction with the iron sulfide contained in the particles whereby the Fe of the elec- 3,8 64,223 6 trolyte and the iron sulfide is converted to Fe and 3. The process of claim 1 wherein the coal contains S. R28 2. The process of claim 1 wherein the Fe in the 4. The process of claim I wherein the coal Contains electrolyte solution is present as FeCl which is con- FeS. verted to FeCl;. 5 I a l 

1. A PROCESS FOR EFFECTING THE REGENERATION OF SPENT ELECTROLYTE SOLUTIONS OBTAINED FROM THE IRON PLATING BATHS COMPRISING TH THE STEPS OF: CHARGING COAL PARTICLES CONTAINING IRON SULFIDES TO A REACTION CHAMBER HAVING A PLURALITY OF OPENINGS IN ITS SIDEWALLS, THE SIZE OF THE OPENINGS BEING SMALLER THAN THE SIZE OF THE PARTICLES, ROTATING THE CHAMBER WITH SUFFICIENT ROTATIONAL SPEED TO GENERATE A CENTRIFUGAL FORCE TO CAUSE THE PARTICLES TO BE PROPELLED OUTWARDLY AGAINST THE WALLS OF THE CHAMBER AND BE FIXED THEREON TO FORM A CONTINUOUS BED OF PARTICLES, CHARGING SPENT ELECTROYLTE SOLUTION COMPRISES OF AN AQUEOUS SOLUTION OF FE3+ TO THE ROTATING CHAMBER, THE ELECTROYLTE SOLUTION BEING PROPELLED OUTWARD INTO CONTACT WITH THE PARTICLE BED FIXED ON THE WALLS OF THE CHAMBER AND CAUSED TO MOVE RADICALLY THERETHROUGH UNDER THE ACTION OF CENTRIFUGAL FORCE, THE FE3+ IN THE ELECTROLYTE SOLUTION DURING THE PASSAGE OF THE SOLUTION THROUGH THE PARTICLE LAYER ENTERING INTO CHEMICAL REACTION WITH THE IRON SULFIDE CONTAINED IN THE PARTICLES WHEREBY THE FE3+ OF THE ELECTROLYTE AND THE IRON SULFIDE IS CONVERTED TO FE2+ AND S.
 2. The process of claim 1 wherein the Fe3 in the electrolyte solution is present as FeCl3 which is converted to FeCl2.
 3. The process of claim 1 wherein the coal contains FeS2.
 4. The process of claim 1 wherein the coal contains FeS. 